Manufacturers of permanent photoresist consider an array of functional requirements when developing new materials. Each step, from synthesis through formulation and film processing, impacts the quality and reliability of the finished product. Typically, pattern-cured formulations consist of functionally different source materials which are employed to match pre-set goals for optical, mechanical, thermal and electrical film properties. However, source materials may contribute ionic and other impurities, either resulting from their respective synthesis, or generated as processing by-products. These impurities can pose a corrosion risk following migration to susceptible metal surfaces with which the film is in contact.The goal of this work is to identify and understand corrosion risks presented by mobile ion impurities as a function of bulk film thermo-mechanical properties. For permanent films used in inkjet applications, key material properties include glass transition temperature (T_g), modulus and water permeability. Electrochemical Impedance Spectroscopy (EIS) was used along with Dynamic Mechanical Analysis (DMA), to characterize prototype films. The level of corrosive species present was analytically quantified via Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Our data shows that thermo-mechanical properties of fully cured permanent film have significant impact on preventing corrosion with significant amounts of corrosive species present.